In the course of use of the Internet, it has been known for some time for information to be made accessible to users relating to the availability of another user, for example by means of programs such as ICQ. For example, a user can thus check whether another user is currently at his computer, and/or has switched the computer on and can receive and read text messages in a corresponding manner.
A service such as this is referred to as a presence service. A presence service is in general a service in which presence information relating to a user is managed with the aim of making the presence information accessible to applications, for example computer applications, to other users or to other services. The presence information may relate not only to people, but also to other services, (server) computers, objects etc.
Typical examples of presence information include information about the location, the state, the mood, the communication readiness (willingness) and the communication capability (ability) of a person (or of an object, for example of a server computer). The presence information generally comprises time-dependent functions.
The total of all of the presence information associated with a person or an object is referred to as the presentity of the person or of the object. Furthermore, a set of rules with restrictions may be a component of the presentity which, for example, specifies how and in what circumstances the presence information relating to the presentity may be passed on, interchanged or made known, for example by specifying appropriate access rights.
A presence service may be offered as an autonomous service, or may be combined with another service.
A presence service may be combined with a telecommunications service, for example, since in this case, the communication readiness and/or the communication capability of a (tele)communication partner desired by a user can in fact be checked by the user (a) before setting up a communication link between the user and the communication partner and (b) before interchanging communication data by means of the telecommunications service between the user and the communication partner.
One typical example of a combination of a telecommunication service with a presence service is for a communication link to be set up automatically between the communication terminal being used by the user (who has configured this appropriately) and the communication terminal of the communication partner designed by the user, as soon as a previous communication link to the communication terminal of the desired communication partner has ended, that is to say obviously when there is a change in the state of the communication terminal of the desired communication partner from “busy” to “free”, with the presence service signaling this state change to the communication terminal of the user.
When using a presence service, a user can control the dissemination of his presence information to other users and/or other services and can define groups of users and/or groups of services to which he wishes to make his presence information available entirely or partially, for example restricted by defined conditions. Furthermore, the user has the capability to check presence information of other users. Overall, the user can set up a large number of combinations of interactions between users and services in accordance with his individual wishes.
As mentioned, the Internet offers presence services with basic functionalities, although the various presence services have poor compatibility and can interact with one another only with considerable effort.
The telecommunications standardization committees are currently working on tasks relating to the provision of presence services in mobile radio communication systems.
A presence service for a mobile radio communication system is described in the document 3rd Generation Partnership Project (3GPP): TS 22.141 v6.2.1, Technical Specification Group ‘Services and System Aspects’, Presence Service Stage 1, and in 3rd Generation Partnership Project (3GPP): TS 23.141 v6.6.0, Technical Specification Group ‘Services and System Aspects’, Presence Service, Architecture and Functional Description, which is distinguished by also having functionalities by means of which the specific requirements for mobile radio are taken into account, in addition to the fundamental functionalities which are known from the Internet. For the purposes of the presence information, specific attributes are thus supported, which are important for wire-free communication purposes.
The document 3rd Generation Partnership Project (3GPP): TS 22.141 v6.2.1, Technical Specification Group ‘Services and System Aspects’, Presence Service Stage 1 (Chapter 4) contains, in particular, the specification for a presence service based on the 3GPP (Third Generation Partnership Project) Standard.
Typically, a presence service is provided by a network component, for example a mobile radio communications system, which network component is typically referred to as a presence server and manages the presentity of a person (or object).
That instance, for example the mobile radio subscriber appliance of a user, which is checking the presence information for a person or an object is referred to as the watcher. The watchers are subdivided into fetchers (watchers on one occasion), pollers (regular watchers) and subscribed watchers.
A watcher is, for example, in the form of a software program which is run on a mobile radio subscriber appliance. A subscribed watcher is a watcher which requests that information corresponding to a presentity be transmitted to it when there is a change to the presence information. For this purpose, a subscribed watcher must register with a presence server. For example, it sends a message to a presence server by means of which the subscribed watcher requests to be informed about any change to the presence information contained in the presentity. The presence server responds to the message, for example, by means of a confirmation message which contains the current presence information for the presentity.
If the presence information contained in the presentity subsequently changes, then the subscribed watcher is informed about this change by the presence server by means of an appropriate message.
A fetcher is a watcher which requests presence information about a presentity only once. The fetcher accordingly sends a message to a presence server, and the presence server responds by means of a further message, which contains the requested presence information.
A poller is a watcher which regularly checks the presence information relating to a person/object.
Presence information may be transmitted in the form of complete data records, that is to say the presence information relating to a presentity may always be transmitted completely. If, however, a watcher relatively frequently receives presence information relating to a specific presentity from a presence server, as in the case in particular with a subscribed watcher, then it is also possible to transmit to the watcher only that presence information which has changed since presence information relating to this presentity was last transmitted.
As mentioned, a watcher is sent presence information only when this watcher has the necessary right for this purpose. A user can restrict the checking of his presence information by means of appropriate access rights, and can thus control the passing on of the presence information.
When the presence information relating to a presentity changes, then all of the subscribed watchers which have requested to be informed about the change to the presence information are informed about the change at the same time (or at least close to the same time).
Particularly in the context of a mobile radio communication system, this is disadvantageous when two subscribed watchers, for example, attempt as a reaction to the information about the change to the presence information to set up a communication link to the person/object corresponding to that presentity (for example when the change to the presence information comprises the person/object now being available). If the subscribed watchers are in the form of suitable communication terminals, and the users of the communications terminals have implemented appropriate user settings, this can be carried out completely automatically, that is to say without any interaction with the user. However, if only a single communication link can be set up to the person/object, then a communication link can be set only between one of the subscribed watchers (or between a mobile radio subscriber appliance) and the person/object.
A user who is acting as a subscribed watcher, that is to say has requested by means of his mobile radio subscriber appliance that appropriate change information is sent to his mobile radio subscriber appliance whenever there is a change to the presence information relating to a person/object, may, for example, choose to be informed about the change to the presence information by audible signaling, for example by his mobile radio subscriber appliance emitting a pipping tone.
When the person/object becomes available in a situation such as this (since, for example, an existing communication link to that person/object has been cleared and a communication link can now be set up to him or it), then this is signaled to the user, for example by means of audible signaling. However, if a further subscribed watcher is automatically setting up a communication link to the person/object, then the presence information relating to that person/object changes again after a short time (to “not available”), without the user having time to himself set up a communication link to that person/object. Since the second change to the presence information is also signaled audibly to the user, the user's mobile radio subscriber appliance produces two audible signals for the user shortly after one another, although these are useless for that user and are typically only disturbing.
Conversely, if the person/object whose presence information is requested is a user to whom attempts to set up communication links to him are signaled (“ringing signaling”), then, when a plurality of subscribed watchers attempt to set up a communication link to that user once he or it has become available the attempt to set up a communication link (ringing) is signaled repeatedly even after one of the subscribed watchers (obviously the fastest) was successful in setting up a communication link to him or it.
Overall, this results in a large number of unnecessary signaling activities, both to the subscribed watchers who are informed about the frequently changing presence information worthlessly, and to the user for example by audible ringing signaling.
This leads on the one hand to unnecessary load on the communications network by the transmission of worthless transmissions to the subscribed watchers and to a low level of user friendliness.
EP 1441486 A2 describes a presence service system in which a plurality of watchers may ask to be informed about changes to presence information. A rule is used to determine the sequence in which the watchers are informed when the presence information changes. For example, the watcher who is the first to make the request is the first to be informed about a change to the presence information.